1. Field of the Invention
The invention relates to antennas generally, and more specifically, to microwave dish-type receiving antennas for recreational vehicle use.
2. Description of the Prior Art
In the prior art, the mounting of antennas on vehicles has been variously addressed. It has been recognized that, during transport, it is highly desirable for an antenna structure to be oriented from its operating position to a position affording reduced air resistance and reduced potential for damage from overhanging trees and other objects.
One prior art arrangement for use with a relatively simple vertical antenna to lower it to a horizontal position is shown in U.S. Pat. No. 4,101,897. Although that disclosure does not apply to the field of invention addressed by the invention, it does serve to show recognition of the desirability of re-orienting vehicle-mounted antennas generally, during transport.
German patent No. 2,204,448 entitled "mobile Satellite Tracking Aerial" shows structures for re-orienting a microwave dish-type antenna into a housing for transport but does not make use of the reflector dish to close the housing as contemplated by the invention.
The state of the art in transportability augmentation for dish type antenna systems is further shown by U.S. Pat. No. 4,309,708. In that disclosure the dish is broken into halves for transport, but no housing structure for it is provided.
Another arrangement for "stowing" a dish type antenna for transport is disclosed in U.S. Pat. No. 3,412,404. In that disclosure, the dish antenna is simply directed downward to make it less subject to interferences from tree branches, low bridges, etc., as it is transported on the vehicle to which it is mounted.
Dish type antennas are common in the radar art, and in recent years have found use in television receiving systems where the signal is received from a geosynchronous satellite. Some of the aforementioned references contemplate radar applications where heavier structures and scanning mechanisms are usually incorporated. The satellite receiving application, on the other hand, does not include continuous scanning, but does require azimuth and elevation orientation mechanisms for accurate and stable direction of the boresite of the antenna toward the satellite.
Another arrangement for downwardly reorienting a vehicle mounted, satellite communication, dish type antenna for transport is shown in Japanese patent No. 55-53903(A). As with the other aforementioned references, no structures for weather protection or significant reduction of wind resistance during transport are shown or intended.
With the increasing popularity of television satellite reception systems, there has been a tendency to apply the available technology in connection with recreational vehicles. Such vehicles also have achieved considerable popularity and accordingly, a need has developed for practical, inexpensive and readily adaptable systems for dish antenna installation on recreational vehicles so that the vacationer/traveller can enjoy satellite-transmitted television programs. The parabolic reflector dish with feed at its focus is widely used for the purpose because of its high gain and discrete beam characteristics. State of the art low noise preamplification is also commonly located at the feed point. In remote areas (away from metropolitan centers), there is often no other television reception available.
Certain recreational vehicles, notably the so-called "house trailer", are constructed with great attention to lightness and are aerodynamically designed to permit towing at highway speeds without excessive fuel consumption by the towing vehicle. One popular "house trailer" has an aluminum outer skin laterally rounded with generally light-weight supporting structures. For mounting even light weight antenna structures on such vehicles, it is important to distribute the resulting roof load over an area rather than relying on point load mountings. Such point mounting can easily result in progressive damage to the roof and water leaks at the mounting points.
The manner in which the invention advances the art in the described field will be understood as this description proceeds.